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11-06-2009, 07:28 PM
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#1
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Junior Member
Join Date: Nov 2009
Location: ohio
Posts: 16
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potential load cal
on one circuit of recepticals how do you measure the full potentail load, is it full load for the first receptical then half for the next then quarter for the rest?
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11-06-2009, 07:36 PM
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#2
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child please.....
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 2,968
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I'm not sure I understand the question? You want to know how much a circuit is rated for?
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11-06-2009, 07:37 PM
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#3
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Senior Member
Join Date: Feb 2009
Location: us
Posts: 699
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Quote:
Originally Posted by tie003uk
on one circuit of recepticals how do you measure the full potentail load, is it full load for the first receptical then half for the next then quarter for the rest?
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For load calculations only, each rec. is counted as 180 VA. Each double duplex is 360 VA
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11-06-2009, 07:42 PM
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#4
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Junior Member
Join Date: Nov 2009
Location: ohio
Posts: 16
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Quote:
Originally Posted by mcclary's electrical
For load calculations only, each rec. is counted as 180 VA. Each double duplex is 360 VA
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sorry coming from the uk to usa are you calling a double duplex 2 rec in a 2 gang box?
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11-06-2009, 07:44 PM
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#5
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child please.....
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 2,968
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Quote:
Originally Posted by tie003uk
sorry coming from the uk to usa are you calling a double duplex 2 rec in a 2 gang box?
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Yeah that would be 360va.
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11-06-2009, 07:45 PM
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#6
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Junior Member
Join Date: Nov 2009
Location: ohio
Posts: 16
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thanks
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11-06-2009, 07:46 PM
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#7
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child please.....
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 2,968
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Is this a commercial application?
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11-06-2009, 07:51 PM
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#8
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Junior Member
Join Date: Nov 2009
Location: ohio
Posts: 16
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nah just a question. for load on lights you just add them up but for recepticals there is no load conected at this time to measure, so was just asking. i can remember one of my bosses saying back in england that to cal the full load of a rec circuit you have full load at the first rec then half at the next then i forget the rest and there is a something if you have a fused spur on the line and all that good stuff that you might not understand with you being in the usa.thanks
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11-06-2009, 07:53 PM
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#9
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child please.....
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 2,968
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If its a residence, then there is no limit to the amount of recepts. you can put on a circuit. You just know how many general purpose circuits are required by the load calc for the whole house.
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11-06-2009, 07:57 PM
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#10
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Junior Member
Join Date: Nov 2009
Location: ohio
Posts: 16
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as a general rule we only put 12 rec on a 100ft branch in uk and use 2.5mm cable which would be 12gauge wire here in the usa and we also wire the rec in a loop from service panel and then from the last rec return to the service
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11-06-2009, 08:00 PM
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#11
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child please.....
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 2,968
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Quote:
Originally Posted by tie003uk
as a general rule we only put 12 rec on a 100ft branch in uk and use 2.5mm cable which would be 12gauge wire here in the usa and we also wire the rec in a loop from service panel and then from the last rec return to the service
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Gotcha. Yeah, I don't put 30 on a circuit, It just depends on what I feel like doing that day.
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11-06-2009, 08:04 PM
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#12
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Junior Member
Join Date: Nov 2009
Location: ohio
Posts: 16
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i just added 4 two bulb lights to a receptical circuit and was concerned about overload and stress on the cable.
oh and one more for you why is it ok to conect neutral and ground together at the service but not ok at the fixture?
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11-06-2009, 08:14 PM
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#13
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child please.....
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 2,968
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Objectional current.You would create a parallel path to ground. Metal parts of the fixture aren't allowed to carry current.
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11-06-2009, 08:20 PM
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#14
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Junior Member
Join Date: Nov 2009
Location: ohio
Posts: 16
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but they are always going to be carrying the neutral into the ground even if its not conected at the fixure because its conected together at the service.
if you have old wire with no gorund you have to conect a bonding jumper to neutral.
so going back to my first question whats the load on the rec's. i can't just add 12 15A rec together its not done like that.how and what?
Last edited by tie003uk; 11-06-2009 at 08:25 PM.
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11-06-2009, 08:28 PM
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#15
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child please.....
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 2,968
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You should never hook a "jumper" from a neutral. It creates a parallel path. There is no current on the metal part of the fixture b/c it is bonded at the service.
As far as the load, for commercial it 180 va per recept. For residential you need to perform a load calc to determine the minimum number of circuits. There is no max recepts per circuit in residential .
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11-06-2009, 08:32 PM
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#16
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Junior Member
Join Date: Nov 2009
Location: ohio
Posts: 16
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thats just nutts.....
forgive me as i am getting to know how they do things over here and i am apply for a union job and they are giving me training
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11-06-2009, 08:33 PM
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#17
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Senior Member
Join Date: Sep 2009
Location: kentucky
Posts: 2,028
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Potential load cal
Quote:
Originally Posted by tie003uk
i just added 4 two bulb lights to a receptical circuit and was concerned about overload and stress on the cable.
oh and one more for you why is it ok to conect neutral and ground together at the service but not ok at the fixture?
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If you connect the neutral, which IS a circuit conductor, to the equipment ground, beyond the service, the fixture can also be a parallel path of circuit current. If a person happens to be working on that fixture, they can become a parallel path of circuit current, as well. Not good.
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11-06-2009, 08:42 PM
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#18
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Junior Member
Join Date: Nov 2009
Location: ohio
Posts: 16
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as i said before if you have a circuit with only hot and neutral and no ground you have to conect neutral to ground to provide some form of protection
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11-06-2009, 08:45 PM
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#19
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child please.....
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 2,968
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Quote:
Originally Posted by tie003uk
as i said before if you have a circuit with only hot and neutral and no ground you have to conect neutral to ground to provide some form of protection
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That is bad. You can become part of the path if you do this. You aren't protecting anything, you make it worse.
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11-06-2009, 08:52 PM
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#20
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Senior Member
Join Date: Feb 2009
Location: us
Posts: 699
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Quote:
Originally Posted by tie003uk
as i said before if you have a circuit with only hot and neutral and no ground you have to conect neutral to ground to provide some form of protection
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says who??????? that's wrong
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